                 {:transaction? false})
     (loop [transformations (butlast (:transformations current-dataset-version))
            columns initial-columns
-           full-execution-log []
+           full-execution-log [] ;; TODO: remove not in use!
            tx-index 0]
       (if (empty? transformations)
         (let [new-dataset-version-id (str (util/squuid))]

                                                                                           "created" (Instant/ofEpochMilli (System/currentTimeMillis))
                                                                                           "changedColumns" (diff-columns previous-columns
                                                                                                                          columns))))})
    (when data-groups-to-be-created
      (let [max-group-order     (apply max (conj (map :group-order data-groups) 1000))
            adapted-data-groups (map-indexed (fn [i item]
                                               (let [idx        (inc (+ i max-group-order))

  2. grab all data-group columns
  3. apply-operation
  4. separate transformation data-group columns from the others"
  [{:keys [tenant-conn claims] :as deps}
   {:keys [transformation data-groups]}]
  (let [columns-in-transformation (columns-used (w/keywordize-keys transformation) (reduce into [] (map :columns data-groups)))
        _  (ensure-one-data-group-related transformation columns-in-transformation data-groups)
        column-name (first columns-in-transformation)
        data-group (datagroup-by-column data-groups column-name)
        source-table (:table-name data-group)
        other-dgs-columns (reduce (fn [c dg] (if (= (:id dg) (:id data-group))
                                               c (into c (:columns dg)))) [] data-groups)
        previous-columns (into (vec (:columns data-group)) other-dgs-columns)
        {:keys [success? message execution-log error-data data-groups-to-be-created] :as res}
        (try-apply-operation deps source-table previous-columns transformation)
        columns (let [other-dgs-columns-set (set other-dgs-columns)]
                  (reduce (fn [container column]
                            (if (contains? other-dgs-columns-set column)
